We are investigating host and parasite factors which interact to produce schistosome lesions, through: purification of schistosome vitellaria granules, and study of their biochemical characteristics; study of enzymes and biochemical pathways instrumental in schistosome egg shell formation; artificial lung granuloma models using schistosome eggs or antigen adsorbed onto carrier particles for the study of pathogenesis and modulating factors affecting granulomas including immunopotentiators; comparison of schistosome pathogenicity in different trematode and/or host species under controlled conditions; immunofluorescent studies of the localization of schistosome antigens in host or parasite tissues and their relationship to pathology; and the effect of drugs, and immunosuppressive measures on schistosome lesions. In addition we have begun a study on the mechanisms of immunity to schistosomula in mice.